Hello,
I am quite puzzled by some info regarding BTU and power consumption in some Cisco datasheets. For example, let's take the datasheet of the Cisco Catalyst 3560-CX (... it would also work with a 2960-CX).
I see the following:
|
Cisco Catalyst 3560-CX
|
|
|
Watts
|
KVA
|
BTU
|
BTU - manually calculated
(W*3.412142)
|
|
3560CX-8TC-S
|
30
|
0.05
|
170.6
|
102 BTU/h
|
|
3560CX-12TC-S
|
30
|
0.05
|
170.6
|
102 BTU/h
|
|
3560CX-8PC-S
|
280
|
0.3
|
1023.61
|
955 BTU/h
|
I calculate the heat dissipation from the true power consumption (in watt) and find a dissipation that is actually lower than the one Cisco provides. Are we questioning the laws of thermodynamics here? Can this device generate more heat than it consumes power?
When I divide the Cisco heat dissipation (BTU/3.41), the result is matching the Cisco apparent power (e.g. 170,6 BTU/h / 3.41 = 50 VA). To my knowledge, heat dissipation should be calculated based on the actual power drawn by the unit (in W).
Is Cisco using the apparent power to be on the safe side? Is there any reason to proceed that way?
Thanks
